1. Field of the Invention
The invention relates generally to a safety latch means for securing together respective parts of a pressure vessel housing. More particularly, the invention pertains to a safety latch means for easily and conveniently securing, in a fail-safe manner, the removable cover member to the shell member of a filter assembly.
A filter assembly of the type to which the invention is directed typically and broadly includes a pressure vessel defined by a filter housing having inlet means for the introduction of liquid and/or gas, filter means disposed in the housing for filtering the introduced medium and outlet means for allowing the purified medium to exit from the housing. For purposes of convenience in servicing the assembly, in replacing the filter means, and in gaining access to the interior of the filter assembly, such a housing is typically formed of more than one member, at least one of the members being separable or removable from the remainder of the housing, such as a removable cover member or lid. While this arrangement is highly advantageous for the ease of accessibility which it allows, it does, however, possess certain critical disadvantages.
The provision of a separable member, such as a removable cover member, creates the possibility for potentially violent separation of the cover member from the remainder of the filter housing due to high pressures exerted thereon by the liquid and/or gas introduced into the filter housing. The resulting damage to personnel and equipment associated with an occurrence of this kind presents a serious safety hazard, with potentially grave and costly consequences which severely limit commercial utility and acceptance of the filter assembly. It is thus imperative that the filter assembly include reliable and effective means for securing together the members forming the pressure vessel or filter assembly housing. In the case of a removable cover member, previous attempts have been made to secure the cover member to the remainder of the filter housing by means of a closure clamp. An attendent drawback to utilization of a closure clamp is that there is usually no way to prevent separation of the cover member from the filter housing when the closure clamp fails, or is loosened, prior to venting the pressurized liquid or compressed gas from the housing. The equally great safety hazard posed with this device has similarly resulted in user dissatisfaction and has detracted from its commercial success. Other efforts toward circumventing the possibility of the cover member being blown from the filter housing have generally involved numerous parts and complex assembly, thereby requiring skilled personnel and making them difficult, inconvenient and costly to use.
The present invention addresses and overcomes the foregoing problems and disadvantages by providing a unique safety latch means for reliably and positively securing a removable cover member to the shell member of a filter housing. The safety latch means requires the removable cover member to engage and lock onto pin members provided on the shell member before a locking clamp is able to be attached. Moreover, external brackets formed, respectively, on the cover member and the shell member are required to be aligned before the locking clamp is able to be applied. The safety latch means insures proper engagement of the cover member with the pin members because alignment of the external brackets is not possible unless the cover member is correctly locked in position on the pin members. The safety latch means provides for fail-safe operation of a filter assembly, or other pressure vessel, in that, if the locking clamp fails or is loosened without prior venting of pressure from the filter assembly, the cover member is permitted to move a small amount in relation to the shell member, so as to allow for the venting of pressure, but will not separate or be blown from the shell member.
2. Brief Description of the Prior Art
It is known in the prior art to provide means for securing a removable cover or lid member to a pressure vessel. For example, U.S. Pat. No. 180,365, issued on Jul. 25, 1876 to Myers, discloses a lid having slots formed therein for engagement with pins provided on a body or pressure vessel. Similar types of locking arrangements are shown in U.S. Pat. No. 1,238,013, issued on Aug. 21, 1917 to Harper; U.S. Pat. No. 1,814,572, issued on Jul. 14, 1931 to Shaffer; U.S. Pat. No. 1,948,771, issued on Feb. 27, 1934 to Rucker; and, U.S. Pat. No. 2,185,897, issued on Jan. 2, 1940 to Krause et al.
The prior art also teaches means for securing together respective housing components in a filter assembly. For instance, U.S. Pat. No. 3,321,085, issued on May 23, 1967 to Moorhead, is directed to a water filter comprising upper and lower housing parts having bosses which must be aligned in order for the respective parts to be secured together by means of wing nuts.
U.S. Pat. No. 3,608,726, issued Sept. 28, 1971 to Crowther, teaches a liquid filter wherein a lid member is attached to a body member by means of cooperating lugs and slots.
Finally, U.S. Pat. No. 3,746,171, issued on Jul. 17, 1973 to Thomsen, is directed to a filter assembly wherein interacting cam means provided on the clamping collar and head serve to prevent complete separation of the filter unit in the event of partial loosening of the collar.
The prior art thus fails to teach or suggest a safety latch means, particularly adapted to a filter assembly, which is characterized by locking means for securing a removable cover member to a shell member, external brackets formed, respectively, on the cover and shell members and being adapted for alignment when the locking means is properly engaged, and a locking clamp for securing the cover and shell members together, the locking clamp being adapted to be attached to the filter assembly only when the brackets are correctly aligned and, hence, the locking means properly engaged.